The hard drive is what it is for. What is HDD, hard drive and hard drive. Hard disk software errors

Cache memory or as it is called the buffer memory of the hard disk. If you do not know what it is, then we will be happy to answer this question and tell you about all the available features. This is a special type of RAM that acts as a buffer for storing previously read, but not yet transmitted data for their further processing, as well as for storing information that the system accesses most often.

The need for transit storage appeared due to the significant difference between the bandwidth of the PC system and the speed of reading data from the drive. Also, cache memory can be found on other devices, namely video cards, processors, network cards and others.

What is the volume and what does it affect

The buffer size deserves special attention. HDDs are often equipped with 8, 16, 32 and 64 MB cache. When copying large files between 8 and 16 MB, there will be a significant difference in performance, but between 16 and 32 it is less noticeable. If you choose between 32 and 64, then it will hardly be there at all. It should be understood that the buffer is often subjected to heavy loads, and in this case, the larger it is, the better.

Modern hard drives use 32 or 64 MB, less today can hardly be found anywhere. For a regular user, both the first and second values ​​will suffice. Moreover, in addition to this, performance is also affected by the size of its own built-in cache. It is he who increases the performance of the hard disk, especially with a sufficient amount of RAM.

That is, in theory, the larger the volume, the better the performance and the more information can be in the buffer and not load the hard drive, but in practice everything is a little different, and the average user, except in rare cases, will not notice much difference. Of course, it is recommended to choose and buy the largest size devices, which will greatly improve the performance of your PC. However, this should be done only if financial opportunities allow.

Purpose

It is intended for reading and writing data, however, on SCSI disks, in rare cases, you need to enable write caching, since by default it is set that write caching is disabled. As we said before, volume is not a critical factor in improving performance. To increase the performance of the hard drive, it is more important to organize the exchange of information with the buffer. In addition, it is also fully influenced by the functioning of the control electronics, prevention of occurrence, etc.

The most frequently used data is stored in the buffer memory, while the volume determines the capacity of this very stored information. Due to the large size, the performance of the hard drive increases significantly, since the data is loaded directly from the cache and does not require physical reading.

Physical reading - direct system access to the hard disk and its sectors. This process is measured in milliseconds and takes quite a long amount of time. At the same time, the HDD transfers data more than 100 times faster than when requested by physical access to the hard drive. That is, it allows the device to work even if the host bus is busy.

Main advantages

Buffer memory has a number of advantages, the main one of which is fast data processing that takes a minimum amount of time, while physical access to the drive sectors requires a certain amount of time until the disk head finds the required piece of data and starts reading it. Moreover, the hard drives with the largest storage can significantly unload the computer's processor. Accordingly, the processor is used minimally.

It can also be called a full-fledged accelerator, since the buffering function makes the hard drive work much more efficiently and faster. But today, with the rapid development of technology, it is losing its former importance. This is due to the fact that most modern models have 32 and 64 MB, which is enough for the normal functioning of the drive. As mentioned above, you can overpay the difference only when the difference in cost corresponds to the difference in efficiency.

Finally, I would like to say that the buffer memory, whatever it is, improves the performance of this or that program or device only if there is multiple access to the same data, the size of which is no larger than the cache size. If your work at the computer is associated with programs that actively interact with small files, then you need the HDD with the largest storage.

How to find out the current cache size

All you need is to download and install the free program HDTune... After starting, go to the "Information" section and at the bottom of the window you will see all the necessary parameters.

If you buy a new device, then all the necessary characteristics can be found on the box or in the attached instructions. Another option is to look online.

This article will only talk about hard disks (HDD), that is, about media on magnetic disks. The next article will be about SSD.

What is a hard drive

Traditionally, let's take a look at the definition of a hard drive on Wikipedia:
Hard disk (screw, hard drive, hard disk drive, hard disk drive, HDD, HMDD) is a random access storage device based on the principle of magnetic recording.
They are used in the vast majority of computers, as well as separately connected devices for storing backup copies of data, as file storage, etc.
Let's figure it out a bit. I like the term "hard disk drive". These five words convey the whole point. HDD is a device, the purpose of which is to store the data recorded on it for a long time. The HDD is based on hard (aluminum) disks with a special coating, onto which information is recorded using special heads.
I will not consider in detail the recording process itself - in fact, this is the physics of the last grades of school, and I am sure you have no desire to delve into this, and the article is not about that at all.
Let's also pay attention to the phrase: "random access" which, roughly speaking, means that we (the computer) can read information from any part of the railway at any time.
It is important that the HDD memory is not volatile, that is, it does not matter whether the power is connected or not, the information recorded on the device will not disappear anywhere. This is an important difference between permanent computer memory and temporary memory (RAM).
Looking at the hard drive of a computer in real life, you will not see any disks or heads, since all this is hidden in a sealed case (hermetic zone). Externally, the hard drive looks like this.
I think you understand what HDD is. Move on.

Why does a computer need a hard drive

Let's take a look at what an HDD is in a computer, that is, what role it plays in a PC. It is clear that it stores data, but how and what. Here we highlight the following functions of the hard drive:
- Storage of OS, user software and their settings;
- User files storage: music, video, images, documents, etc;
- Using part of the hard disk space to store data that does not fit in RAM (paging file) or storing the contents of RAM during sleep mode;
- As you can see, a computer hard drive is not just a dump of photos, music and videos. The entire operating system is stored on it, and in addition, the hard disk drive helps to cope with the RAM load, taking on some of its functions.

What does a hard drive consist of?

We partially mentioned about the composite hard disk, now we will deal with this in more detail. So, the main components of the HDD:
- Case - protects the hard drive mechanisms from dust and moisture. As a rule, it is sealed so that the very moisture and dust do not get inside;
- Discs (pancakes) - plates made of a certain alloy of metals, coated on both sides, on which data is recorded. The number of plates can be different - from one (in budget versions) to several;
- Engine - on the spindle of which pancakes are fixed;
- Block of heads - a construction of interconnected levers (rocker arms), and heads. The part of the hard disk drive that reads and writes information to it. For one pancake, a pair of heads is used, since both the upper and lower parts are working;
- Positioning device (actuator) - a mechanism that drives the head block. Consists of a pair of permanent neodymium magnets and a coil located at the end of the head block;
- Controller - an electronic microcircuit that controls the operation of the HDD;
- Parking area - a place inside the hard drive next to the disks or on their inner part, where the heads are lowered (parked) during idle time, so as not to damage the working surface of the pancakes.
Such is the simple device of the hard disk. It was formed many years ago, and no fundamental changes have been made to it for a long time. And we move on.

How a hard drive works

After power is supplied to the HDD, the engine, on the spindle of which the pancakes are fixed, begins to spin up. Having picked up the speed at which a constant air flow is formed at the surface of the disks, the heads begin to move.
This sequence (first, the discs spin up, and then the heads begin to work) is necessary so that due to the formed air flow, the heads float above the plates. Yes, they never touch the surface of the discs, otherwise the discs would be instantly damaged. However, the distance from the surface of the magnetic plates to the heads is so small (~ 10 nm) that you cannot see it with the naked eye.
After starting, first of all, it reads service information about the state of the hard disk and other necessary information about it, located on the so-called zero track. Only then does the work with the data begin.
Information on the computer's hard disk is recorded on tracks, which, in turn, are divided into sectors (such as a pizza cut into pieces). To write files, several sectors are combined into a cluster, which is the smallest place where a file can be written.
In addition to this "horizontal" partitioning of the disk, there is also a conditional "vertical". Since all heads are combined, they are always positioned over the same track number, each over its own disc. Thus, during the operation of the HDD, the heads seem to draw a cylinder.
While the HDD is running, it essentially performs two commands: read and write. When it is necessary to execute a write command, the area on the disk where it will be performed is calculated, then the heads are positioned and, in fact, the command is executed. Then the result is checked. In addition to writing data directly to the disk, information also goes to its cache.
If the controller receives a command to read, first of all, it checks for the presence of the required information in the cache. If it is not there, the coordinates for positioning the heads are calculated again, then the heads are positioned and the data is read.
After completion of work, when the power supply to the hard drive disappears, the heads are automatically parked in the parking zone.
This is, in general terms, how a computer's hard drive works. In reality, everything is much more complicated, but an ordinary user, most likely, does not need such details, so we will finish with this section and move on.

Types of hard drives and their manufacturers

Today, there are actually three main manufacturers of hard drives on the market: Western Digital (WD), Toshiba, Seagate. They fully cover the demand for devices of all types and requirements. The rest of the companies either went bankrupt, or were taken over by one of the main three, or repurposed.
If we talk about the types of HDDs, they can be divided as follows:

1. For laptops - the main parameter is the device size of 2.5 inches. This allows them to be compactly located in the laptop case;
2. For PC - in this case it is also possible to use 2.5 "hard drives, but as a rule, 3.5" are used;
3. External hard drives - devices that are separately connected to a PC / laptop, most often acting as a file storage.
There is also a special type of hard drives for servers. They are identical to conventional PCs, but may differ in connection interfaces and higher performance.

All other divisions of HDD into types come from their characteristics, so we will consider them.

Hard drive specifications

So, the main characteristics of a computer hard drive:

Volume is a measure of the maximum amount of data that can be stored on a disk. The first thing to look at when choosing an HDD. This figure can reach 10 TB, although 500 GB - 1 TB is more often chosen for a home PC;
- Form Factor - The size of the hard drive. The most common are 3.5 and 2.5 inches. As mentioned above, 2.5 ″ in most cases are installed in laptops. They are also used in external HDDs. 3.5 ″ is installed on the PC and on the server. The form factor also affects the volume, since a larger disk can fit more data;
- Spindle speed - at what speed the pancakes rotate. The most common are 4200, 5400, 7200 and 10000 rpm. This characteristic directly affects the performance, as well as the price of the device. The higher the speed, the higher both values;
- Interface - the method (type of connector) of connecting the HDD to the computer. The most popular interface for internal hard drives today is SATA (older computers used IDE). External hard drives are usually connected via USB or FireWire. In addition to those listed, there are also such interfaces as SCSI, SAS;
- Buffer size (cache memory) - the type of fast memory (by the type of RAM) installed on the hard disk controller, intended for temporary storage of the most frequently accessed data. The buffer size can be 16, 32 or 64 MB;
- Random access time - the time during which the HDD is guaranteed to perform writing or reading from any part of the disk. It fluctuates from 3 to 15 ms;

In addition to the above characteristics, you can also find such indicators as:

Data transfer rate;
- The number of input-output operations per second;
- Noise level;
- Reliability;
- Resistance to shocks, etc .;
That's all about the characteristics of the HDD.

The hard drive, or hard drive, is the main and very important part of the computer. It stores not only the operating system that controls the computer, but also all the information of a client or several clients. It often happens that the value of information is many times greater than the cost of the hard drive itself, but also of the computer as a whole. Therefore, the security of information largely depends on the quality and reliability of such a storage device. A modern hard drive looks like the picture shown.

What is a hard drive?

So, what exactly is a storage device, on the performance of which the well-being and good mood of its owner depends? In fact, a hard drive is a high-tech equipment that stores digital information even when the computer is turned off.

More precisely, the hard drive consists of several magnetic disks, on which information is applied and read using a magnetic head. These heads, together with the magnetic disks, are in a vacuum, which allows the drive to work without the influence of the external environment on the process of writing and reading information.

What types of hard drives are there?

So, we found out that a hard drive is a storage device for a computer. Now let's see what types of HDD are. First of all, it should be noted that hard drives can be divided into two categories:

• External drives that can be connected to any computer via a USB interface. Somehow they resemble a USB flash drive, only in large sizes. Such hard drives do not need special software.
• Internal HDD drives are installed inside computers and have specific connectors for both power supply and information transfer.

Internal HDDs are also divided into several categories. There are several criteria by which a hard drive can be classified. This is the physical size of the hard drive. There are three standard sizes:

• 5.5 inches. Usually, hard drives of this standard size are used in stationary computers, where there is a lot of free space.
• 3.5 inches is used mainly in laptops where space is limited and the amount of memory required is large.
• 2.5 inches are used in ultrabooks where space is very limited.

Another sign by which drives are classified is the data exchange protocol between the hard drive and the computer. What protocols can the hard drive use? They are as follows:

• IDE is an old version of the protocol that was used mainly on computers and laptops until 2000.
• SCSI is a contemporary of IDE, a faster version of storage management that was used primarily in server machines. Required special drivers to use such hard drives.
• SATA is a modern version of the protocol that has several options and has a high speed of writing and reading information. It is used in almost all modern computer systems.

Hard drive problems

One of the most frightening messages that can be seen on the screen says that the computer cannot see the hard drive. Why is this so intimidating for computer users? In the event of such a malfunction, the device does not load the operating system, therefore, practically no actions provided for by this system can be performed.

What can cause such a malfunction? The simplest problem that leads to this result is a violation of the integrity of the power loops or system interface. Often times, dust or dirt getting inside such a connector will cause this malfunction. And most experienced users are not particularly scared when such a message appears, but simply dock the power and interface connectors. This inscription may look something like the one shown in the photo above.

Hard drive not visible for BIOS

When such a problem occurs, the first thing to determine is whether the problem is physical or software. How to find out? After a message appears that the computer does not see the hard drive, you need to reboot the machine and enter the BIOS. What is BIOS? This is a program that is written in the ROM of the computer's motherboard. It is loaded even before the operating system and determines the peripheral devices with which the motherboard will work. To load the BIOS, you need to press the corresponding key on the keyboard, usually the DEL or F2 button. After entering BIOS, you can see the following picture.

This photo shows that the BIOS did not detect any hard drives on the computer. In this case, the problem described above could occur, and the computer, being disconnected from the power cable or interface, is invisible to the BIOS. On the other hand, any malfunction in the hard drive control board will lead to such a problem. Moreover, if it is possible to solve this problem, then only in the appropriate service center. It is almost impossible to eliminate it on your own at home.

Windows 7 does not see the hard drive

But there are times when the hard disk is visible to the BIOS, and the operating system does not boot, or Windows is constantly rebooting. When does this happen? Then, when, when working with the operating system, one of the system files was deleted or an error occurred during overwriting, and the file is not read correctly. Physical damage to the hard drive, scratch or chipping of the disk surface may also occur. If one of the system files was located in this place, then the operating system will not be able to read it and will give, as system administrators say, a blue screen of death, which suggests rebooting the system. If the error persists, it is best to contact your system administrator. Sometimes, such software errors are easy enough to fix without reinstalling the operating system. But it happens that they are fatal, and they can only be fixed by a complete reinstallation of the system. To solve this kind of problems, they usually use system utilities that restore software errors. What are these programs?

Hard disk software errors

There are many programs for recovering software errors, which can be divided into two categories. The first includes utilities that are inside the system, and they can be used after the operating system is fully loaded. These are sets of programs for servicing hard drives.

For example, how do you maintain a Windows 7 hard drive? You can service your drive directly from the program. To do this, just go to "My Computer" and select the disk that we want to serve. Click on the "Properties" tab and see the following picture, shown in the photo above.

Hard disk maintenance programs

As you can see in the picture, the user is offered three utilities:

• Checking for errors.
• Disk archiving.

Errors are corrected only by the first program, and the rest will simply service this disk. But there are programs that work without an operating system. The advantage of such utilities is that they can service the disk even when the operating system does not boot. For example, one of these programs is called FDISK and was developed by Microsoft as a utility for servicing disks before installing the operating system. It is used by experienced computer users Norton Disk Doctor, and there are actually a lot of such programs, so the choice largely depends on the preferences of a particular person. Before installing "Windows" from the hard drive, it is advisable to service it with a similar program and correct possible errors.

Recovery of hard drives

Often, many users are faced with the problem of recovering data on a problematic hard drive. As already mentioned above, often the information stored on it is valued much more than the hard drive itself. Therefore, the work of recovering lost data is not only valuable, but also highly paid. Much depends on how the information disappeared. It is important to remember how Windows deletes information from your hard drive.

The operating system does not erase information that the user wants to remove. It simply deletes the hard drive's table of contents, which allows you to find this information. Such a table of contents is called a FAT table. And if after that other information was not recorded on the body of the Windows 10 hard drive, then it is quite easy to recover it. There are many programs that can do this job. According to many users, one of the best is Acronis Recovery Expert.

Hard disk backup

Be that as it may, no user wants to be constantly under the threat that valuable information is in danger. Therefore, efforts are made to minimize risks. What can be done? Backing up useful information of the hard drive as a whole or a sector of the hard drive helps to solve this problem.

What backup methods are there?

• In manual mode. The user independently chooses what information and when the program will save. Some companies in their own offices prefer to back up data at the end of the work shift. But at the same time, there is a danger of losing information that has accumulated during the day.
• Automatic backup. At the same time, the program includes how often and what should be copied and saved.
• Creation of a mirrored RAID array, which in parallel on another hard disk stores all the information from the main hard drive. If the latter fails, you can easily use a mirror.

Choosing a hard drive

Paying great attention to the safety of information, do not forget about the choice of the manufacturer of the hard disk, as well as the technical parameters that characterize the quality of this hard drive. If we talk about the brand of the drive manufacturer, then it is worth choosing a better-known company, although such a hard drive will cost a little more. Some users prefer Seagate.

If we talk about technical parameters, then, all things being equal, it is worth paying attention to the speed of reading and writing information. Sometimes these data will help to make a choice in favor of one or another hard drive.

Summarize

So, a hard drive is a storage device for very valuable and important information in a computer. Therefore, you need to make a lot of effort in order to choose a quality hard drive. You should also take care of regular maintenance of your device. In addition, it is important to pay attention to the security of information, if any, on your computer. If you make all these efforts, then your hard drive will serve you for a long time, and the information on it will be completely safe. The operation of your device is completely in your hands, so take all measures for its normal operation.

Hard disks, or, as they are also called, hard drives, are one of the most important components of a computer system. Everyone knows about it. But not every modern user even knows, in principle, how a hard drive functions. The principle of operation, in general, is quite simple for a basic understanding, but there are nuances here, which will be discussed later.

Questions about the purpose and classification of hard drives?

The question of purpose is, of course, rhetorical. Any user, even the most entry-level one, will immediately answer that the hard drive (aka hard drive, aka Hard Drive or HDD) will immediately answer that it serves to store information.

In general, it is true. Do not forget that on the hard disk, in addition to the operating system and user files, there are boot sectors created by the OS, thanks to which it starts, as well as some labels by which you can quickly find the necessary information on the disk.

Modern models are quite diverse: ordinary HDDs, external hard drives, high-speed solid-state drives SSD, although they are not usually referred to as hard drives. Further, it is proposed to consider the device and the principle of operation of the hard disk, if not in full, then at least in such a way that it would be enough to understand the basic terms and processes.

Please note that there is also a special classification of modern HDDs according to some basic criteria, among which the following can be distinguished:

• way of storing information;
• media type;
• way of organizing access to information.

Why is a hard drive called a hard drive?

Today, many users are wondering why they call them small arms hard drives. It would seem, what can be in common between these two devices?

The term itself appeared back in 1973, when the world's first HDD appeared on the market, the design of which consisted of two separate compartments in one sealed container. The capacity of each compartment was 30 MB, which is why the engineers gave the disk the codename "30-30", which was fully consonant with the brand of the popular 30-30 Winchester rifle at that time. True, in the early 90s in America and Europe, this name practically fell out of use, but it still remains popular in the post-Soviet space.

The device and principle of operation of the hard disk

But we got distracted. The principle of operation of a hard disk can be briefly described as the processes of reading or writing information. But how does this happen? In order to understand how a magnetic hard disk works, you first need to study how it works.

The hard drive itself is a set of plates, the number of which can vary from four to nine, connected to each other by a shaft (axis) called a spindle. The plates are located one above the other. Most often, the materials for their manufacture are aluminum, brass, ceramics, glass, etc. The plates themselves have a special magnetic coating in the form of a material called platter, based on gamma ferrite oxide, chromium oxide, barium ferrite, etc. Each such plate is about 2 mm thick.

Radial heads are responsible for writing and reading information (one for each plate), and both surfaces are used in the plates. For which it can be from 3600 to 7200 rpm, and two electric motors are responsible for the movement of the heads.

In this case, the basic principle of the computer's hard disk is that information is not written anywhere, but in strictly defined locations, called sectors, which are located on concentric tracks or tracks. To avoid confusion, uniform rules apply. It means that the principles of hard disk drives, from the point of view of their logical structure, are universal. So, for example, the size of one sector, accepted as a unified standard all over the world, is 512 bytes. In turn, the sectors are divided into clusters, which are sequences of adjacent sectors. And the peculiarities of the principle of operation of a hard disk in this regard are that the exchange of information is just carried out by whole clusters (an integer number of chains of sectors).

But how does the reading of information take place? The principles of operation of a hard disk drive are as follows: using a special bracket, the reading head moves in a radial (spiral) direction to the desired track and, when rotated, is positioned over a given sector, and all heads can move simultaneously, reading the same information not only from different tracks , but also from different disks (plates). All tracks with the same serial numbers are usually called cylinders.

At the same time, one more principle of hard disk operation can be distinguished: the closer the read head is to the magnetic surface (but does not touch it), the higher the recording density.

How is information written and read?

Hard disks, or hard drives, were called magnetic because they use the laws of physics of magnetism, formulated by Faraday and Maxwell.

As already mentioned, a magnetic coating is applied to the plates of a non-magnetically sensitive material, the thickness of which is only a few micrometers. During operation, a magnetic field appears, which has a so-called domain structure.

The magnetic domain is a magnetized region of the ferroalloy strictly limited by the boundaries. Further, the principle of operation of a hard disk can be briefly described as follows: when the effect of an external magnetic field occurs, the intrinsic field of the disk begins to orient itself strictly along the magnetic lines, and when the effect is terminated, zones of remanent magnetization appear on the disks, in which the information that was previously contained in the main field is stored ...

The reading head is responsible for creating an external field during writing, and when reading, the remanent magnetization zone, being opposite the head, creates an electromotive force or EMF. Then everything is simple: the change in EMF corresponds to one in the binary code, and its absence or termination corresponds to zero. The time of EMF change is usually called a bit element.

In addition, purely for reasons of computer science, a magnetic surface can be associated as a certain point sequence of bits of information. But, since it is absolutely impossible to calculate the location of such points, it is necessary to install some predetermined markers on the disk, which helped to determine the desired location. The creation of such labels is called formatting (roughly speaking, breaking the disk into tracks and sectors, combined into clusters).

The logical structure and principle of operation of the hard disk in terms of formatting

As for the logical organization of the HDD, formatting comes first here, in which two main types are distinguished: low-level (physical) and high-level (logical). Without these stages, there is no need to talk about bringing the hard drive into working condition. How to initialize a new hard drive will be discussed separately.

Low-level formatting involves a physical impact on the surface of the HDD, which creates sectors located along the tracks. It is curious that the principle of operation of a hard disk is such that each created sector has its own unique address, including the number of the sector itself, the number of the track on which it is located, and the number of the side of the plate. Thus, when organizing direct access, the same RAM addresses directly to a given address, and does not look for the necessary information over the entire surface, due to which speed is achieved (although this is not the most important thing). Please note that when performing low-level formatting, absolutely all information is erased, and in most cases it cannot be recovered.

Logical formatting is another matter (on Windows systems, this is quick formatting or Quick format). In addition, these processes are applicable to the creation of logical partitions, which are a kind of area of ​​the main hard disk that works in the same way.

Logical formatting primarily affects the system area, which consists of the boot sector and partition tables (Boot record), file allocation table (FAT, NTFS, etc.) and the root directory (Root Directory).

Information is written to sectors through the cluster in several parts, and one cluster cannot contain two identical objects (files). Actually, the creation of a logical partition, as it were, separates it from the main system partition, as a result of which the information stored on it is not subject to change or deletion when errors and failures appear.

Main characteristics of HDD

I think, in general terms, the principle of the hard disk is a little clear. Now let's move on to the main characteristics, which give a complete picture of all the capabilities (or disadvantages) of modern hard drives.

The principle of operation of a hard disk and the basic characteristics can be completely different. To understand what we are talking about, let us single out the most basic parameters that characterize all the information storage devices known today:

• capacity (volume);
• performance (speed of access to data, reading and writing information);
• interface (connection method, controller type).

Capacity is the total amount of information that can be recorded and stored on the hard drive. The HDD manufacturing industry is developing so rapidly that today hard drives with volumes of about 2 TB and more have come into use. And, as it is believed, this is not the limit.

The interface is the most significant characteristic. It determines exactly how the device is connected to the motherboard, which controller is used, how it reads and writes, etc. The main and most common interfaces are IDE, SATA and SCSI.

Disks with IDE interface are not expensive, but among the main disadvantages are the limited number of simultaneously connected devices (maximum four) and low data transfer rates (even if support for direct access to Ultra DMA memory or Ultra ATA protocols (Mode 2 and Mode 4) Although it is believed that their use can increase the read / write speed up to 16 Mb / s, but in reality the speed is much lower. In addition, to use the UDMA mode, you need to install a special driver, which, in theory, should complete with motherboard.

Talking about the principle of operation of the hard drive and its characteristics, one cannot ignore and which is the successor to the IDE ATA version. The advantage of this technology is that the read / write speed can be increased up to 100 MB / s using the high-speed Fireware IEEE-1394 bus.

Finally, the SCSI interface is the most flexible and fastest compared to the previous two (read / write speeds up to 160 Mb / s and above). But such hard drives are almost twice as expensive. But the number of simultaneously connected storage devices is from seven to fifteen, the connection can be made without powering off the computer, and the cable length can be about 15-30 meters. Actually, this type of HDD is mostly used not in user PCs, but on servers.

Performance, which describes the transfer rate and I / O throughput, is usually expressed in transfer time and the amount of sequential data transferred, and is expressed in MB / s.

Some additional parameters

Speaking about what the principle of operation of a hard disk is and what parameters affect its operation, one cannot ignore some additional characteristics, on which the performance or even the service life of the device may depend.

Here in the first place is the rotation speed, which directly affects the search and initialization (recognition) of the desired sector. This is the so-called latent seek time - the interval during which the desired sector is rotated towards the read head. Today, several standards have been adopted for spindle speed, expressed in rpm with dwell times in milliseconds:

• 3600 - 8,33;
• 4500 - 6,67;
• 5400 - 5,56;
• 7200 - 4,17.

It is easy to see that the higher the speed, the less time it takes to search for sectors, and in physical terms, to turn the disk before setting the required plate positioning point for the head.

Another parameter is the internal baud rate. On the outer lanes, it is minimal, but it increases with a gradual transition to the inner lanes. Thus, the same defragmentation process, which is moving frequently used data to the fastest areas of the disk, is nothing more than transferring it to an internal track with a faster read speed. The external speed has fixed values ​​and directly depends on the interface used.

Finally, one of the important points is related to the hard disk having its own cache memory or buffer. In fact, the principle of operation of a hard disk in terms of using a buffer is somewhat similar to RAM or virtual memory. The larger the cache memory (128-256 KB), the faster the hard drive will work.

Main requirements for HDD

There are not so many basic requirements that in most cases are imposed on hard drives. The main thing is long service life and reliability.

The main standard for most HDDs is considered to be a service life of about 5-7 years with an operating time of at least five hundred thousand hours, but for high-end hard drives this figure is at least a million hours.

In terms of reliability, the S.M.A.R.T self-test function is responsible for this, which monitors the state of individual elements of the hard drive, carrying out constant monitoring. On the basis of the collected data, even a certain forecast of the occurrence of possible malfunctions in the future can be formed.

It goes without saying that the user should not stand aside either. So, for example, when working with HDD, it is extremely important to observe the optimal temperature regime (0 - 50 ± 10 degrees Celsius), to avoid shocks, shocks and drops of the hard drive, dust or other small particles getting into it, etc. It is interesting to know that the same particles of tobacco smoke are approximately twice the distance between the read head and the magnetic surface of the hard drive, and the distance between a human hair is 5-10 times.

Initialization issues in the system when replacing the hard drive

Now a few words about what actions should be taken if for some reason the user changed the hard drive or installed an additional one.

We will not fully describe this process, but will dwell only on the main stages. First, the hard drive must be connected and see in the BIOS settings whether the new hardware has been detected, in the disk administration section to initialize and create a boot record, create a simple volume, assign an identifier (letter) to it and perform formatting with the choice of the file system. Only after that the new "screw" will be completely ready for work.

Conclusion

That, in fact, is all that briefly concerns the fundamentals of the functioning and characteristics of modern hard drives. The principle of operation of an external hard drive was not considered in principle here, since it practically does not differ in anything from what is used for stationary HDDs. The only difference is the method of connecting the additional drive to your computer or laptop. The most common is the USB interface, which is directly connected to the motherboard. At the same time, if you want to ensure maximum performance, it is better to use the USB 3.0 standard (the port inside is colored blue), of course, provided that the external HDD itself supports it.

As for the rest, it seems that many have understood at least a little how a hard disk of any type functions. Perhaps, too much was given above, even more from the school course of physics, nevertheless, without this, it will not be possible to fully understand all the basic principles and methods inherent in the technologies of production and use of HDD.

Hello! Finally, I found time to please you with new material! I apologize for not writing for so long. The fact is that I worked on one project, which I will talk about in the future (subscribe to blog updates).

Why do you have to buy a new hard drive? Everyone may have their own reasons, but this basically means that the speed of work and the loading of programs has noticeably decreased, or there is not enough space to write new information to the computer. Whatever the reason for buying a new hard drive, everyone has something to think about before making a purchase. So let's figure it out how to choose a hard drive for your computer and what to consider before purchasing. And below we will analyze a real example of buying a hard drive. After all, a sudden and thoughtless decision can lead to the fact that the new HDD will not satisfy your needs.

How to choose a hard drive for your computer

Hard drives can be internal, which are installed in a computer, and external. Internal ones are regular (3.5 "for computers) and laptops (2.5" form factor). This article will focus specifically on internal drives.

Hard disk space

Gone are the disks with 40 or 80 GB of memory. Now on the market the volume of a hard disk is measured in hundreds of gigabytes and terabytes. How much disk space should you choose? Much depends on what kind of work is being done on the computer and how much space you really need. You have to pay more for a larger volume. It is better to start with real needs with 20-50% headroom, rather than how much disk space your friend or neighbor installed, since he may actually need a lot of disk space.

Considering that hard drives with a volume of less than 500GB are no longer found in stores, we will assume that this is the minimum sufficient volume. That much space is enough for normal home use, work and leisure. If you need to download large amounts of information from the Internet, for example torrents, and if you are installing weighty games, then take a disk with a capacity of 1TB or more. Even larger disks are useful for those who store large archives. Well, in general, they themselves know why they need such a disk 🙂

I am sometimes asked how many megabytes are in 1 gigabyte, or how many gigabytes are in a terabyte. Everything is simple, but funny. In fact, there are 1024 bytes in one kilobyte, i.e. 1K = 1024B. One megabyte has 1024 kilobytes, one gigabyte has 1024 megabytes, and one terabyte has 1024 gigabytes. But the manufacturers of hard drives went for a little trick and took not 1024, but the number 1000 for the multiplier, supposedly so that buyers would not get confused 🙂

Yeah, cool! Only now, after installing a drive with a capacity of, say, 500GB, we will see only 465GB available! Because the computer still counts gigabytes as expected!

This is such an embarrassment, so you don't have to run to give the hard drive back to the store, because now you know how many megabytes are in one gigabyte.

I think it's clear how to choose a hard drive in terms of volume, but I want to warn against buying a disk with a volume of more than 2TB. If your motherboard is running a regular BIOS, then you still won't see more than 2TB! For such models, UEFI is required instead of BIOS. To check this and carefully read its interface and settings in the "Boot" menu. If you come across the word "UEFI", then consider yourself lucky 🙂 Or just read the instructions for the computer motherboard.

But is everything limited to disk space? No, there is one more important point - speed.

Hard disk speed

A disk with a large capacity does not yet guarantee fast loading of programs. It just allows you to accommodate more information. The speed of loading programs and their execution is the speed of the hard disk itself. Although, in principle, the capacity also affects the speed indirectly. Because the larger the volume, the higher the recording density, and, accordingly, it takes less time to read the data block. Simply put, a large disk will almost always be faster than a smaller disk, all other things being equal.